A Hydrodynamic Wheatstone Bridge For Use As A Teaching Tool In Instrumentation Laboratory Courses

Undergraduate engineering students often find systems composed of electrical circuits difficult to grasp because variables such as current, voltage, resistance, capacitance, and inductance are not easily visualized as their analogs in mechanical systems. Thus, a Hydrodynamic Wheatstone bridge, using the analogy of flow in pipes, was developed to serve as a teaching tool in the classroom. A series of tests were performed to simulate 1⁄4, 1⁄2, full, and shunted bridge circuits, where the increase or decrease in resistance in the strain gage is analogous to partially closing or opening a valve in a pipe network. The difference in head potential (i.e., ∆V) was measured with manometers located between the valves. The results agree with the 1⁄4, 1⁄2, full, and shunted Wheatstone bridge circuits. Future enhancements include the addition of flow meters to relate water flow to current flow, scaled full turn valves to more accurately represent changing resistances, and a flexible tube section, in place of a valve, to replicate a strain gage in tension.